In general, light-sensitive materials have silver halide emulsion layers which are sensitive to the three primary colors, namely, red, green and blue. Color images are reproduced by a so-called subtractive color process wherein three kinds of color generating agents (couplers) in the emulsion layers generate colors which are complementary to the color sensed by each layer. Color images obtained by photographic processing of this light-sensitive material are generally composed of azomethine dyes or indoaniline dyes which are formed by a reaction between an oxidation product of an aromatic primary amine developing agent and a coupler. Color photographic images thus obtained are not necessarily stable with respect to light, or humidity and heat, and when they are exposed to light for a prolonged period of time or preserved under high temperatures and high humidities, color fading and discoloration of the color images occur, and the color images deteriorate.
Such fading and discoloration of color images are serious drawbacks for recording materials. In order to eliminate these drawbacks, development of couplers which are capable of providing dyes having excellent fastness, and countermeasures such as use of anti-fading agents and use of UV absorbers for preventing images from being deteriorated by ultraviolet rays, and so on have been proposed.
As for the anti-fading agents, there have been known, for example, hydroquinones, hindered phenols, catechols, gallic acid esters, aminophenols, hindered amines, chromanols, indans; ethers or esters wherein the phenolic hydroxyl groups of these compounds are silylated, acylated or alkylated; and metal complexes of these compounds.
Sulfides and sulfoxides of a certain structure, sulfur-containing heterocyclic compounds and tetrahydrothiopyran compounds of a certain structure are disclosed in U.S. Pat. Nos. 4,540,658, 4,880,733, and 4,704,350, British Patent No. 1,410,846, JP-A-54-48536 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-63-43146, JP-A-63-149644, JP-A-62-103642, JP-A-2-208653, JP-A-1-113382, JP-A-1-200255, European Patent Application Nos. 178,794A, 310,551A, 310,552A and 509,311A1, and so on.
Although these compounds are effective for preventing fading or discoloration of color images, their properties fail to meet customers' demands for images of high quality, and excellent effects in color photographs have not yet obtained.